Quadcap Embeddable Database

com/quadcap/sql/NameExpression.java

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package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import java.util.ArrayList;
import java.util.Vector;

import java.sql.SQLException;

import com.quadcap.sql.types.Op;
import com.quadcap.sql.types.Type;
import com.quadcap.sql.types.Value;

import com.quadcap.util.Debug;
import com.quadcap.util.Util;

/**
 * Expression class for names (typically column or function names).
 *
 * @author Stan Bailes
 */
public class NameExpression extends Expression implements Externalizable {
    String                              name;
    boolean                             not     = false;

    /**
     * Default constructor
     */
    public NameExpression() {}
    
    public NameExpression(String name) {
        this.name = name;
    }

    /**
     * I'm a scalar, basically
     */
    public int rank() { return 0; }
    
    public Type getType(Session session, Cursor cursor) throws SQLException {
        String rname = session.getConnection().resolveColname(name, cursor);
        Column c = cursor.getColumn(rname);
        return c.getType();
   }
    
    public Value getValue(Session session, Cursor cursor) throws SQLException {
        Cursor effectiveCursor = cursor;
        if (cursor == null) {
            throw new SQLException("No cursor for name expression: " + name, "42000");
        }
        String rname = session.getConnection().resolveColname(name, cursor);
        Column c = cursor.getColumn(rname);
        if (c == null) {
            throw new SQLException("Bad column: " + name, "Q000S");
        }
        Tuple tc = c.getRelation();
        if (tc instanceof Cursor && !(cursor instanceof StaticCursor)) {
            effectiveCursor = (Cursor)tc;
        }
            
        int col = c.getColumn();
        Row row = effectiveCursor.getRow();
        if (row == null) {
            throw new SQLException("no cursor", "Q000T");
        }
        Value v = row.item(col);
        if (not) v = v.unop(Op.NOT);
        return v;
    }

    public Row getValues(Session session, Cursor cursor) throws SQLException {
        ArrayList v = new ArrayList();
        v.add(getValue(session, cursor));
        return new Row(v);
    }

    public String getName() { return name; }
    
    public void invert() {
        not = !not;
    }

    public void visitSubExpressions(ExpressionVisitor ev) {
    }

    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        name = (String)in.readObject();
    }
    
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(name);
    }

    public String toString() {
        return name;
    }
}